Sorry for the late reply. I've been a tad busy and now am under the weather. Thanks for all the replies here.

It was definitely luminance noise as I could remove it with a slight adjustment. I did actually see it at 100% and then went further for more detail which I know I shouldn't do since ACR sharpening and noise is meant to be seen at 100%.

I guess I was more shocked than anything that I was seeing it all since I didn't see it in Aperture, but they are different beasts so I shouldn't be that surprised.

Anyway, thanks for all the posts and info.

if you look at the aperture version it is a lot less sharp so either it is doing a bit more NR under teh hood or the ACR was doing a bit more sharpening at default